An imaging apparatus is known in the art that detects movement of a common target object or subject contained in a plurality of time-sequentially captured images by extracting several feature points of the subject from one of these images and then extracting corresponding feature points from other images to track these feature points.
For example, JPA No. 2007-142507 discloses a teaching of extracting feature points from a sequence of images and calculating motion vectors of the extracted feature points, to correct image blurs by correcting image-clipping positions from the respective images and then averaging the clipped images. JPA No. 2007-183256 discloses extracting multiple feature points from an image captured by an imaging apparatus and then extracting corresponding feature points from another image captured immediately before or after the above-mentioned image. Tracking the respective feature points in this way makes it possible to measure the position or posture of the imaging apparatus or determine coordinates of a target object accurately even while the imaging apparatus is shaking.
However, conventional methods of tracking the movement of a subject by identifying corresponding feature points of the subject between successive images of the subject generally has a problem that the corresponding feature points can be difficult to find if the subject or target object moves so fast that the consequent images suffer motion blur and thus have reduced contrast. The above-mentioned prior arts do not provide any solution for this problem that can occur when the subject moves at a high speed.